HR: 16:45h
AN: OS44B-04    [Abstracts]
TI: A modeling study using the mineral ballasting tecnique for POC flux prediction in the ocean with a focus on comparison with sediment trap data and interactions with the sediments.
AU: * Howard, M T
EM: mthoward2@wisc.edu
AF: Department of Atmospheric and Oceanic Sciences, University of Wisconsin-Madison, Center for Climatic Research, 1225 W. Dayton St., Madison, WI 53706
AU: Winguth, A M
EM: amwinguth@facstaff.wisc.edu
AF: Department of Atmospheric and Oceanic Sciences, University of Wisconsin-Madison, Center for Climatic Research, 1225 W. Dayton St., Madison, WI 53706
AU: Klaas, C
EM: cklaas@awi-bremerhaven.de
AF: Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, Bremerhaven, D-27570 Germany
AB: The fluxes of POC below the euphotic zone in the ocean are modeled using a mineral ballasting approach with the HAMOCC5.1 Carbon Cycle Model. {\it Armstrong et al.}[2002] and {\it Klaas and Archer}[2003] have shown that particulate organic carbon(POC) fluxes at depths of 2,000m and more in the ocean have a statistically significant correlation to the fluxes of the biominerals CaCO$_{3}$ and opal, and also lithogenic material, at those depths. Utilizing their parameterization, the goal of this study is to improve agreement between modeled POC fluxes and sediment trap data over the previous approach, a distribution curve modified from {\it Martin et al.}[1978] to include an iron dependency. A baseline run of the model with the mineral ballasting parameterization has been integrated for 10,000 years and is compared with a reference run of the model and with data. The long integration time is especially useful for studying the interactions with the sediments. The modeled POC fluxes do not significantly improve in agreement with sediment trap data from the reference run, but the overall distribution of CO$_{2}$ in the ocean does improve. At 3,000m, the modeled CO$_{2}$ is nearly the same as the values from GLODAP data, with model-data differences not exceeding about 60 æmol/kg or 2%. The alkalinity distribution at 3,000m is similar to the reference run and agrees reasonably well with data. In addition to the baseline run of the model with the ballast parameterization, sensitivity experiments were conducted to test the response of the ballast model to changes in the e-folding penetration depth of CaCO$_{3}$ and opal, the sediment dissolution constant, and the PIC:POC ratio. Each of the experiments was integrated 10,000 years to allow for interactions with the sediments. The model was sensitive to each of these parameters, and in the case of increasing the PIC:POC ratio from 0.20 to 0.25, improved the tracer distributions.
DE: 4805 Biogeochemical cycles (1615)
DE: 4806 Carbon cycling
DE: 4842 Modeling
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting